U.S. patent number 5,999,319 [Application Number 09/069,502] was granted by the patent office on 1999-12-07 for reconfigurable compound diffraction grating.
This patent grant is currently assigned to InterScience, Inc.. Invention is credited to James Castracane.
United States Patent |
5,999,319 |
Castracane |
December 7, 1999 |
Reconfigurable compound diffraction grating
Abstract
A reconfigurable compound diffraction grating is fabricated
using microelectomechanical systems (MEMS) technology. The compound
grating structure can be viewed as the superposition of two
separately configured gratings. A common lower electrode is placed
beneath selected beam elements, known as deflectable beams, to
achieve the desired grating configuration (i.e. every other, every
third, every fifth, etc.) of the beams in the primary grating.
These deflectable beams alone comprise a secondary, lower
resolution grating structure. The beam elements are linked to a
common upper electrode. Voltage applied across the electrodes
creates an electrostatic force that pulls the selected beams down
toward the underlying electrode. Changing the vertical position of
the selected beams with respect to the other stationary beams
presents a different ruling spacing distribution to the incoming
radiation. By changing this distribution, the diffracted power
among individual diffraction orders of the wavelengths is altered.
Controlling the diffracted signal in this way allows for specific
diffraction passbands to be fixed on a particular detector or a
particular area of a detector. Automated adjustments to the rulings
can be very rapidly, which would significantly simplify and reduce
the time necessary for complete spectral analysis previously
achieved by mechanical movement of diffraction gratings.
Inventors: |
Castracane; James (Albany,
NY) |
Assignee: |
InterScience, Inc. (Troy,
NY)
|
Family
ID: |
46203351 |
Appl.
No.: |
09/069,502 |
Filed: |
April 29, 1998 |
Current U.S.
Class: |
359/573; 359/572;
359/855 |
Current CPC
Class: |
G01J
3/02 (20130101); G01J 3/0235 (20130101); G01J
3/1804 (20130101); G02B 5/1828 (20130101); G01J
3/0256 (20130101); G02B 6/29314 (20130101) |
Current International
Class: |
G02B
5/18 (20060101); G02B 6/34 (20060101); G02B
005/18 () |
Field of
Search: |
;359/573,572,291,295,855,224 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
James Castracane and Mikhail Gutin, "MEMS-based microgratings:
preliminary results of novel configurations", SPIE vol. 3276, Mar.
1998, pp. 196-206. .
Elmers Hung and Stephen D. Senturia, "Leveraged Bending for Full
Gap Positioning with Electrostatic Actuation", Solid-State Sensor
and Actuator Workshop, Jun. 8-11, 1998, Hilton Head, S.C., pp.
83-86. .
C.S. Gudeman, B. Staker, and M. Daneman "Squeeze Film Damping of
Doubly Supported Ribbons in Noble Gas Atmospheres", Solid-State
Sensor and Actuator Workshop, Jun. 8-11, 1998, Hilton Head, S.C.,
pp. 288-291..
|
Primary Examiner: Henry; Jon
Attorney, Agent or Firm: Yablon; Jay R. Simkulet; Michelle
D.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 60/045,483, filed May 2, 1997.
Claims
I claim:
1. An array of reconfigurable diffraction gratings comprising at
least one diffraction grating, each said diffraction grating
comprising:
a plurality of substantially parallel diffraction beams further
comprising a plurality of stationary beams and a plurality of
deflectable beams; in an initial position, said stationary beams
substantially residing within a stationary beam plane and said
deflectable beams substantially residing within a deflectable beam
plane slightly elevated with respect to said stationary beam plane;
and said deflectable beams occupying regular, periodic positions
among said diffraction beams and separated from one another within
each such period by at least one successive stationary beam;
a plurality of lower electrode extension beam means each associated
with, substantially parallel to, and beneath, one of said
deflectable beams; and
voltage differential means applying a selected voltage differential
between each of said lower electrode extension beam means and its
associated deflectable beam thereby moving said deflectable beams
and hence said deflectable beam plane by a selected distance, from
said initial position.
2. The grating array of claim 1, each said diffraction grating of
said grating array further comprising:
a plurality of second lower electrode extension beam means each
associated with, substantially parallel to, and beneath, one of
said stationary beams; and
second voltage differential means applying a second selected
voltage differential between each of said second lower electrode
extension beam means and its associated stationary beam thereby
moving said stationary beams and hence said stationary beam plane
into said initial position and enabling selection of said initial
position.
3. The grating array of claim 2, wherein for each said diffraction
grating of said grating array:
the selected voltage differential applied between each lower
electrode extension beam means and its associated deflectable beam,
and the second selected voltage differential applied between each
second lower electrode extension beam means and its associated
stationary beam, is individually controllable; whereby
the separation of said deflectable beams from one another within
each said period by said at least one successive stationary beam
may be actively, electronically reconfigured.
4. The grating array of claim 1, wherein said deflectable beams of
at least one diffraction grating of said grating array are
so-separated from one another by exactly one stationary beam.
5. The grating array of claim 1, wherein said deflectable beams of
at least one diffraction grating of said grating array are
so-separated from one another by exactly two stationary beams.
6. The grating array of claim 1, wherein said deflectable beams of
at least one diffraction grating of said grating array are
so-separated from one another by exactly four stationary beams.
7. The grating array of claim 1, said grating array comprising
exactly one said diffraction grating.
8. The grating array of claim 1, said grating array comprising at
least two of said diffraction gratings, wherein the periodic
position separations of said deflectable beams of at least one of
said diffraction gratings is different than the periodic position
separations of said deflectable beams of at least another one of
said diffraction gratings.
9. The grating array of claim 1, further comprising a reflective
coating on at least an upper surface of said diffraction beams of
at least one of said diffraction gratings and on at least an upper
surface of a base of said at least one of said diffraction
gratings.
10. The grating array of claim 1, wherein said grating is
fabricated using microelectromechanical systems technology.
11. The grating array of claim 1 in combination with a
spectrometer, wherein said grating is incorporated into said
spectrometer and used for controlling grating spacing for said
spectrometer.
12. The grating array of claim 1 in combination with a laser,
wherein said grating is incorporated into said laser and used for
tuning laser line sequencing of said laser.
13. The grating array of claim 1, wherein a ratio of spacing
between each successive diffraction beam to a width of each said
diffraction beam is substantially between 1/4 to 1 and 2 to 1.
14. A method for reconfiguring an array of reconfigurable
diffraction gratings comprising at least one diffraction grating,
comprising the steps of, for each said diffraction grating of said
grating array:
applying a selected voltage differential between a plurality of
substantially parallel deflectable beams and a plurality of lower
electrode extension beam means each associated with, substantially
parallel to, and beneath, one of said deflectable beams; and
moving thereby, said deflectable beams and hence a deflectable beam
plane within which said deflectable beams reside, by a selected
distance, from an initial position slightly elevated with respect
to a plurality of stationary beams substantially residing within a
stationary beam plane;
a plurality of substantially parallel diffraction beams comprising
said plurality of deflectable beams and said plurality of
stationary beams; and
said deflectable beams occupying regular, periodic positions among
said diffraction beams and being separated from one another within
each such period by at least one successive stationary beam.
15. The method of claim 14, comprising the further steps of, for
each said diffraction grating of said grating array:
applying a second selected voltage differential between each of
said stationary beams and a plurality of second lower electrode
extension beam means each associated with, substantially parallel
to, and beneath, one of said stationary beams; and
moving thereby, said stationary beams and hence said stationary
beam plane into said initial position and enabling selection of
said initial position.
16. The method of claim 15, comprising the further step of, for
each said diffraction grating of said grating array:
individually controlling the selected voltage differential applied
between each lower electrode extension beam means and its
associated deflectable beam, and the second selected voltage
differential applied between each second lower electrode extension
beam means and its associated stationary beam; whereby
the separation of said deflectable beams from one another within
each said period by said at least one successive stationary beam
may be actively, electronically reconfigured.
17. The method of claim 14, further comprising so-separating said
deflectable beams of at least one grating of said grating array
from one another by exactly one stationary beam.
18. The method of claim 14, further comprising so-separating said
deflectable beams of at least one grating of said grating array
from one another by exactly two stationary beams.
19. The method of claim 14, further comprising so-separating said
deflectable beams of at least one grating of said grating array
from one another by exactly four stationary beams.
20. The method of claim 14, said grating array comprising exactly
one said diffraction grating.
21. The method of claim 14, said grating array comprising at least
two of said diffraction gratings, the periodic position separations
of said deflectable beams of at least one of said diffraction
gratings being different than the periodic position separations of
said deflectable beams of at least another one of said diffraction
gratings.
22. The method of claim 14, further comprising providing a
reflective coating on at least an upper surface of said diffraction
beams of at least one grating of said grating array and on at least
an upper surface of a base of said at least one grating of said
grating array.
23. The method of claim 14, comprising the further step of
fabricating said grating array using microelectromechanical systems
technology.
24. The method of claim 14, comprising the further steps of
incorporating said grating array into a spectrometer and using said
grating array for controlling grating spacing for said
spectrometer.
25. The method of claim 14, comprising the further steps of
incorporating said grating array into a laser and using said
grating array for tuning laser line sequencing of said laser.
26. The method of claim 14, comprising the further step of
providing a ratio of spacing between each successive diffraction
beam to a width of each said diffraction beam substantially between
1/4 to 1 and 2 to 1.
Description
FIELD OF THE INVENTION
This invention relates to the field of diffraction gratings, and
particularly to adjustable and compound diffraction gratings to
simplify measurements in multiple spectral passbands.
BACKGROUND OF THE INVENTION
Various designs of micromechanical systems capable of light
diffraction have been previously developed for a number of
applications. One class of micromechanical diffraction elements,
the grating, can be used for various electro-optical applications
such as spectroscopy or as spatial light modulators for
applications such as display technology and optical signal
processing.
A spatial light modulator is presented in U.S. Pat. No. 5,061,049
whereby a reflective element is electrostatically controlled by
electrodes to achieve various angles of beam deflection. The
primary advantage taught in this patent is the small deflection
angle and uniform beam deflection achieved by using two sets of
electrodes designated address electrodes and landing electrodes.
The landing electrodes minimize the stress to the deflected
element. The simple design of the reflective element provides ample
means of beam deflection but does not address the diffraction
requirements of spectroscopy.
A deformable grating apparatus is presented in U.S. Pat. Nos.
5,459,610 and 5,311,360 both by Bloom et al. The grating apparatus
is presented as a means to modulate incident light rays primarily
for display technology applications. An array of beams, at
initially equal heights and with reflective surfaces, are supported
at predetermined fractions of incident wavelength above a similarly
reflective base. Below the base is a means of electrostatically
controlling the position of the beams by supplying an attractive
force which will deflect all of the beams or every other beam to a
secondary position. The diffraction of the incident light is
dependent upon the position of the reflective beam elements. The
primary application of the grating apparatus presented in these
prior art patents is as a spatial light valve. Control of the
deformable grating apparatus is limited for spectroscopic
applications.
OBJECTS OF THE INVENTION
It is an object of the invention disclosed herein to provide a
compound diffraction grating developed through
microelectromechanical systems (MEMS) processing that can be
reconfigured in real time to allow for sequential analysis of
multiple passbands thereby simplifying spectroscopic measurements
for multispectral analysis.
It is also an object of the invention to provide a reconfigurable
compound diffraction grating to enable wavelength tuning in a laser
cavity via voltage adjustments to the grating.
SUMMARY OF THE INVENTION
The present invention provides a reconfigurable compound
diffraction grating fabricated using MEMS technology. The
implementation of this reconfigurable compound diffraction grating
in a miniature spectrometer will simplify multispectral analysis
measurements.
A common lower electrode is placed beneath selected reflective beam
elements to achieve the desired grating configuration (i.e. every
other, every third, every fifth, etc.). The same beam elements
which have the electrode underneath are elevated above the other
beam elements in the grating's initial position. The elevation of
periodic selected grating elements is the basis for the design of
the compound grating structure, which can be viewed as two gratings
superimposed on one another, namely, a lower resolution diffraction
grating consisting of only the elevated beams and a higher
resolution grating consisting of all of the beams.
All of the beam elements are linked to a common upper electrode.
Voltage applied across the upper and lower electrodes creates an
electrostatic force that pulls the selected beams down toward the
underlying electrode. Changing the vertical position of the
selected beams with respect to the other stationary beams presents
a different ruling distribution to the incoming radiation. By
changing this distribution spacing, the diffracted power among
individual diffraction orders of the wavelengths is altered.
Controlling the diffracted signal in this way allows for specific
diffraction passbands to be fixed on a particular detector or a
particular area of a detector.
Therefore a diffraction grating of this design can be sent a series
of calibrated voltage pulses to change the ruling distribution of
the grating through the desired configurations for complete
spectral analysis. These adjustments can be made very rapidly in an
automated manner, which significantly simplifies and reduces the
time necessary for complete spectral analysis previously achieved
by mechanical movement of the diffraction grating, or by
interchanging several gratings.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the invention believed to be novel are set forth in
its associated claims. The invention, however, together with
further objects and advantages thereof, may best be understood by
reference to the following description taken in conjunction with
the accompanying drawing(s) in which:
FIG. 1 is a two dimensional top view of the reconfigurable compound
diffraction grating.
FIG. 2 is a two dimensional side view of a deflectable beam and a
stationary beam in the initial position of the compound diffraction
grating.
FIG. 3 is an exploded isometric, cutaway view of the reconfigurable
compound diffraction grating in an initial position.
FIG. 4 is an exploded isometric, cutaway view of the reconfigurable
compound diffraction grating in a secondary position.
FIG. 5 is a schematic cross sectional view of the reconfigurable
compound diffraction grating with every other beam being a
deflectable beam with an associated lower electrode extension
beam.
FIG. 6 is a schematic cross sectional view of the reconfigurable
compound diffraction grating with every third beam being a
deflectable beam with an associated lower electrode extension
beam.
FIG. 7 is a schematic cross sectional view of the reconfigurable
compound diffraction grating with every fifth beam being a
deflectable beam with an associated lower electrode extension
beam.
FIGS. 8a and 8b is a representation of light diffracting from the
compound grating in the initial undeflected and secondary deflected
positions.
FIG. 9 is a top view of an example of an array of reconfigurable
compound diffraction gratings.
DETAILED DESCRIPTION
The primary basic function of a diffraction grating in any
application is to separate incident light by wavelength. The
general operation of a diffraction grating is sensitive to the
wavelength of incident light and input angle and will diffract
specific wavelengths of light at specific angles based on the
grating design.
The reconfigurable, compound diffraction grating 1 is shown from a
top view in FIG. 1, and from a cutaway isometric view in FIG. 3. A
base 100, typically made of silicon, supports a frame 102. A lower
electrode lead 104 lies on the base 100, and runs parallel to and
below the frame 102, as shown in FIG. 3. An upper electrode lead
106, runs through two corners of the frame 102 along the top
surface 302 of said frame 102, generally perpendicular to the
extension of a set of diffraction beams 108 supported at their ends
by the frame 102.
This set of beams 108 comprises both stationary beams 210 and
deflectable beams 212. The planes of the beams 108, run
substantially parallel to each other and substantially
perpendicular to the sides of the frame 102, by which they are
supported. The set of beams 108, are of substantially uniform
thickness, width and length. The beams 108, are much longer than
they are wide and thick. The beams 108, are spaced along the frame
102, at periodic intervals. Both the base 100, and the top surface
of the set of beams 108, are of a reflective nature.
The upper electrode lead 106, the top surface 302 of the frame 102,
and the set of beams 108 are all electrically connected, and
together comprise an upper electrode. The lower electrode lead 104
and a series of lower electrode extension beams 214 are all
electrically connected, and together comprise a lower electrode.
The frame 102, which is an electrical insulator, enables the
introduction of voltage differentials between the upper electrode
comprising 106, 302 and 108, and the lower electrode comprising 104
and 214.
The deflectable beams 212, can be identified as those in the set of
beams 108, which have the lower electrode extension beams 214,
running underneath them. Also, in the initial undeflected position
shown in FIG. 3, the deflectable beams 212, are in an elevated
plane above the stationary beams 210, although remaining generally
parallel. The relative parallelism is achieved by the excessive
length of all of the beams 108 as compared to their length and
width. This elevation of the deflectable beams 212, is a key
feature in the design of the reconfigurable compound diffraction
grating 1, which can be viewed as the superposition of two grating
structures. The series of deflectable beams 212, comprise a low
resolution grating secondary to the higher resolution primary
grating consisting of the full set of beams 108.
The diffraction of incident light by the reconfigurable compound
diffraction grating is controlled by manipulating the vertical
position of particular individual beams in the set of beams 108,
and in particular, by changing the vertical position of the
deflectable beams 212 while leaving unaltered the vertical position
of the stationary beams 210.
FIG. 2 shows a cutaway side view of the interior of the
reconfigurable compound diffraction grating in which the vertical
elevation of the plane of the deflectable beams 212, over the plane
of the stationary beams 210 is evident. One of the lower electrode
extension beams 214 is shown lying on the base 100, immediately
beneath one of the deflectable beams 212. This deflectable beam 212
is shown in its initial position. As seen in FIG. 2, the majority
of the top surface of the deflected deflectable beam 212, remains
substantially parallel to an adjacent stationary beam 210.
Application of a voltage differential applied between the
deflectable beams 212, and the lower electrode extension 214, would
result in a deflection of the beams 212, in which they would
approach the plane of the stationary beams 210. Of course,
application of different voltages would result in different degrees
(distances) of deflection.
FIG. 3 is a cutaway isometric view of the reconfigurable compound
diffraction grating in an initial, undeflected position. This view
shows exactly how the lower electrode extension beams 214, project
along the base 100 from the lower electrode lead 104, and how the
deflectable beams 212 are positioned directly above the lower
electrode extension beams 214 so that they may be deflected when a
voltage differential is applied between the upper and lower
electrodes generally.
FIG. 4 is a similar cutaway isometric view of the reconfigurable
compound diffraction grating, with the deflectable beams 212
depicted at a deflected position in which the deflectable beams
212, are in the same plane as the stationary beams. Applying a
voltage differential across the two (upper and lower) electrodes
via the upper and lower electrode leads 106 and 104, respectively,
causes the deflectable beams 212 to move towards the lower
electrode extension beams 214. The deflection of the deflectable
beam 212, is proportional to the voltage applied to the lower
electrode lead 104, and therefore to the lower electrode extension
beam 214 electrically connected thereto.
The upper electrodes (comprising 106, 302, and 108 (i.e., 210/212))
are typically fabricated as a unit whole with the rest of the
grating structure typically of a material such as silicon. No
shielding is necessary between the stationary beams, 210, and the
adjacent deflectable beams, 212, since the aspect ratio of the set
of beams, 108, is such that voltage applied to the lower electrode
lead 104, and therefore to the lower electrode extension beam, 214,
is enough to only deflect the deflectable beam, 212.
For descriptive purposes thus far, the stationary beams 210, and
the deflectable beams 212 have been shown alternating every
position in the diffraction grating, which is represented in the
cross sectional schematic view of FIG. 5. Alternative
configurations of the stationary beams 210, and the deflectable
beams 212, may be desired depending on the specific application of
the diffraction grating. Although the diffraction of the incoming
light is altered by changing the vertical position of the
deflectable beams 212, and thereby changing the vertical spacing
between the stationary beams 210, and the deflectable beams 212,
alternative configurations of the stationary beams 210, and the
deflectable beams 212 are beneficial for various parts of the
spectrum. In addition, such configurations can be determined based
on the resolution requirements of the secondary grating structure
that consists of the deflectable beams 212.
FIG. 6 presents an alternative configuration in which the
deflectable beams 212 occupy every third position and the
stationary beams 210 occupy the remaining positions. Similarly,
FIG. 7 presents another alternative configuration in which the
deflectable beams 212 occupy every fifth position and the
stationary beams 210 occupy the remaining positions. The
alternative configurations are not limited to those shown in FIGS.
5, 6, and 7, and indeed, any repetitive periodic pattern could be
incorporated into the grating design and is contemplated by this
disclosure and its subsequent associated claims. From these
configurations, the diffraction of the incoming light is controlled
by the vertical position of the deflectable beams 212.
Using the configuration in which every third beam is deflectable,
as presented in FIG. 6, FIGS. 8a and 8b are respective
representations of the light diffracted from the reconfigurable
diffraction grating 1 in the initial position (FIG. 8a) and as the
beams are deflected to the secondary position where the deflected
and stationary beams are aligned (FIG. 8b). That is, FIG. 8a
represents the initial position of FIG. 3, and FIG. 8b represents
the secondary position of FIG. 4, but with the every-third-beam
spacing of FIG. 6. The diffraction is changed when the beams are
deflected due to the change in the position of the reflective
surface.
FIG. 8a shows the light diffracted from the reconfigurable compound
diffraction grating base 100 in the initial position of the
configuration of every third beam being deflectable. The secondary
diffraction grating consisting of only the deflectable beams 212
causes the diffraction described below as due to 3d spacing. The
primary diffraction grating consisting of the entire set of beams
108, accounts for the diffraction described below as due to d
spacing. The diffraction generated from impinging light, 818,
includes a zero order, 820, a first order (due to 3d spacing where
d is beam spacing), 822, a second order (due to 3d spacing), 824
and a third order/first order superposition (due to 3d spacing and
d spacing, respectively), 826. FIG. 8b shows the diffraction
generated from the grating base 100 when the deflected beams (every
third beam configuration) are moved to their secondary position
where they are aligned with the undeflected beams. In this
configuration only the zero order, 820 and first order (due to d
spacing), 826 are present as a result of impinging light, 818. It
is important to note that FIGS. 8a and 8b are simply illustrative
of how light readings may be taken from this grating, and that many
other variations obvious to someone of ordinary skill are possible
and clearly within the scope of this disclosure and its associated
claims.
The reconfigurable diffraction grating is typically fabricated
using MEMS processing. Current MEMS processing techniques are
capable of features on the scale of 1-2 microns. The most critical
dimension in the operation of the diffraction grating is the width
of the beam. The ruling or grating spacing determines the
resolution of the grating. With the current feature sizes on the
1-2 micron scale, a grating comparable with a medium resolution
(600-1200 grooves/mm) conventional optical grating is produced.
This resolution is ideal for the visible and near-infrared region
of the electromagnetic spectrum and higher wavelengths, as well.
The design of the reconfigurable compound diffraction grating can
be scaled to include wider beams and grating spacings to be useful
in applications in the infrared region of the electromagnetic
spectrum. As the size limitations of the MEMS processing technique
decreases, the reconfigurable diffraction grating will be
applicable below this wavelength, and it is contemplated that the
scaling of the beam width and ruling to such smaller dimensions is
fully encompassed by this disclosure and its subsequent associated
claims.
The use of such a reconfigurable compound diffraction grating could
be incorporated in a miniature spectrometer apparatus, and is part
of this disclosure and its associated claims. In miniaturizing a
spectrometer setup, size, space and simplicity are critical
factors. A grating designed on the scale described above would
greatly minimize the space required. Control of the grating would
also become simplified and automated by the calibrated voltage
sequence applied to change the grating spacing.
The use of such a reconfigurable compound diffraction grating could
also find application in the development of a tunable laser cavity
as well. Conventional gratings are used in laser cavities to tune
the lasers to a specific wavelength, usually by manual rotation.
Use of the reconfigurable compound diffraction grating in the
tunable laser cavity would simplify control of the wavelength
selection to the application of a precalibrated voltage setting and
allow for rapid and automated sequencing between lasing lines. This
too, is contemplated in the scope of this disclosure and its
associated claims.
Presented above is just a single embodiment of the present
invention. Alternative embodiments include variations in the
configuration of beams that establish the rulings of the
diffraction grating. The design presented above can be formed with
a variety of beam widths and spacings between the beams, also known
as grating spacing. For example, these variations include but are
not limited to, beams spaced half a beam width apart, a quarter of
a beam width apart, and twice a beam width apart. All such
variations, and similar variations, are contemplated by this
disclosure and its associated claims.
Another alternative embodiment of the reconfigurable compound
diffraction grating includes coating the set of beams 108, the
upper electrode lead 106, and the lower electrode lead 104, with a
thin film of reflective coating such as gold or aluminum in order
to significantly increase the reflectivity and therefore resultant
signal strength. Coating the top surface of the set of beams 108,
also provides a means of reducing the electrical resistance. This
is particularly important in high frequency applications.
Another alternative embodiment of the present invention includes
expanding the single diffraction grating presented above to an
array of diffraction gratings that would respond to a broader input
signal or have a multitude of beam configurations as presented for
example in FIGS. 5, 6, and 7 available in one array to a single
input signal for parallel processing. One such embodiment is
presented in FIG. 9. The design of the reconfigurable compound
diffraction grating from FIG. 1 is extended in width and replicated
in a 1.times.5 array of diffraction gratings connected by the
common upper electrode lead 106, and a lower electrode lead 104, on
a common base 100. The individual frames 102 and set of beams 108,
are evident in each array grating element.
Yet another alternative embodiment of this invention is the
reconfigurable compound diffraction grating configured with a lower
electrode extension beam 214, under every beam in the set of beams
108, thereby making every beam a deflectable beam 212, wherein some
of the beams 108 are voltage deflected to a position appropriate to
stationary beams 210, while others are voltage deflected to a
position appropriate to deflectable beams 212, as earlier
described. With this design, the voltage applied to the lower
electrode leads 104 can be controlled to individually address each
lower electrode extension 214 to actively reconfigure the
diffraction grating to the appropriate configuration (every other,
every third, every fifth, etc.) for the application in which it is
being used. This advanced design is a natural extension of the
embodiments presented herein and allows a single reconfigurable
compound diffraction grating to satisfy all possible configuration
requirements.
While only certain preferred features of the invention have been
illustrated and described, many modifications, changes and
substitutions will occur to those skilled in the art. It is,
therefore, to be understood that the subsequent associated claims
are intended to cover all such modifications and changes as fall
within the true spirit of the invention.
* * * * *